Fascinating article on chloramine and chlorine removal. The local water here is treated with chloramine. Apparently this is harder to remove than chlorine. The typical carbon block filter is capable of only a few thousand gallons of chloramine removal compared with tens of thousands of gallons of chlorinated water. Clearly this is a lot going on here. The article references a dual pass filtration which removes nearly all the chloramine or chlorine.

This is from Spectra Pure A “ppm-hour” is defined as the exposure of 1 ppm chlorine/chloramine water for 1 hour. Film-Tec quotes 300,000 ppm-hours (six years at 1 ppm) of chloramine resistance for their TFC polyamide (PA) membrane material, but only 200 to 1000 ppm-hours of free chlorine resistance. This indicates that chloramines will not damage Film-Tec membranes, while free chlorine levels must be held below 0.1 ppm to prevent oxidation damage.

This is very informative. Since chloramine is becoming more prevalent, the risk of membrane damage is considerably lessened.

A word of caution here, sodium bisulfite will pickle a Spectra membrane just fine, but it will destroy your $3,600 Clark pump and the life time warranty that came with it.

Interested in what a safer alternative to sodium metabisulphite might be. Our system is a Desalator, and they supply sodium metabisulphite for pickling, but as far as I know, normally that would not get to the pump?